A scroll compressor is widely used to compress a refrigerant, air, or any other given fluid. For example, Japanese Patent Publication No. 3731068 discloses a hermetically sealed scroll compressor. The scroll compressor includes a vertically elongated cylindrical casing, a compression mechanism, and an electric motor. The compression mechanism and the electric motor are housed in the casing. The compression mechanism is arranged over the electric motor and coupled to the electric motor via a drive shaft. The compression mechanism includes a fixed scroll and an orbiting scroll. The orbiting scroll has an end plate including a wrap provided to protrude from the front side thereof and a cylindrical portion provided to protrude from the rear side thereof. The wrap of the orbiting scroll engages with a wrap of the fixed scroll, thereby forming a compression chamber between them. The end plate of the orbiting scroll further has a thrust sliding surface which comes into sliding contact with a thrust sliding surface of the fixed scroll.
The end plate of the orbiting scroll is provided with an oil groove and a communication passage. The oil groove is a recessed groove which opens through the thrust sliding surface of the end plate and is formed to surround the wrap of the orbiting scroll. This oil groove communicates, via the communication passage, with the inner space of the cylindrical portion, which further communicates with an oil reservoir that comes to have a high pressure during operation. The pressure in the compression chamber adjacent to the oil groove is almost as high as the pressure of a low-pressure refrigerant sucked into the compression chamber, and is lower than the pressure in the oil groove. Thus, the pressure difference caused between the oil groove and the compression chamber allows a sufficient amount of lubricating oil to be supplied to the thrust sliding surfaces. This reduces the frictional force produced between the respective thrust sliding surfaces of the orbiting and fixed scrolls, and eventually reduces the power consumption of the electric motor.